This invention relates generally to devices for measuring the coefficient of friction between a sliding piece and a stationary element, and in particular to a device adapted for measuring the coefficient of friction of railroad rail.
Railroad rails are lubricated primarily for two reasons: reduction of wear and reduction of energy consumption. While lubrication has been used on rails in curves for decades, recent discoveries have made it advantageous to lubricate straight or tangent track to reduce locomotive fuel consumption. Conversely, there are some operating situations where lubrication is very undesirable because of a need for high traction by the locomotive and braking of entire trains. Management of lubrication strategies is essential to safe and efficient railroad operations.
A conventional device for measuring friction must be pushed along the track manually by an operator. It can only measure one location on one track at a time. Also, it is very labor-intensive and places the operator out in the elements while measurements are taken.
A device was needed that measured both the running surface (top) and the gage face (side) or corner of both rails. Such a device would preferably provide information on the lubrication condition of four locations as the device was moved along a pair of railroad tracks. Mounting of such a device on a regular piece of railroad maintenance and inspection equipment would increase its utility. The railroads regularly use a modified pickup truck with small railroad wheels attached to inspect railroad tracks. The small railroad wheels guide the pickup truck and its rubber tires provide the traction and motive power. The installation of a coefficient of friction measuring device on the front bumper of such a pickup truck would greatly enhance the utility of such a measuring device. The operator could place the friction measuring device on the rail and drive for miles, collecting data in the process. By using a computer up in the cab of the pickup with electrical connections to the friction measuring device, the operator could observe the electrical responses of the device and discern the actual coefficient of friction as he drives on the rail. The device could also record the measurements for later analysis.
An object of the invention is to provide a simple, accurate, reliable device with minimal maintenance to measure the coefficient of friction to assess lubrication levels. It would be advantageous to assess the levels of lubrication at two locations of both railroad tracks simultaneously. The device is preferably lightweight for ease of installation and easy to use. Preferably, it produces consistent results independent of travel speed or the vehicle to which it is attached. An advantage of the invention described herein is that a lightweight device can be easily mounted to a railroad maintenance vehicle and collect many miles of data reliably, which will enable improved management of rail lubrication on the railroads.